Evidence for the transmission of antimicrobial resistant bacteria between humans and companion animals: A scoping review.

Objective: Transmission of antimicrobial resistant bacteria between people and household pets, such as dogs and cats, is an emerging global public health problem. This scoping review synthesized existing evidence of human-pet bacteria transmission to understand the magnitude and breadth of this issue.

Methods: The search included specific and generic terms for bacteria, resistance, transmission, pets, and humans. Searches were conducted through PubMed, Scopus, Web of Science, CABI Global Health, Networked Digital Library of Theses and Dissertations, Google Scholar. All studies published in English and Mandarin that isolated bacteria from pets (cats and dogs) and humans who had contact with the pets, and reported phenotypic or genotypic antimicrobial sensitivity test results, were included in this review. In cases of bacterial species that are commonly associated with pets, such as and , we also included studies that only isolated bacteria from humans.

Results: After removing duplication, the search captured 9355 studies. A total of 1098 papers were screened in the full-text review, and 562 studies were identified as eligible according to our inclusion criteria. The primary reason for exclusion was the lack of sensitivity testing. The included studies were published between 1973 and 2021. The most common study location was the United States ( = 176, 31.3%), followed by the United Kingdom ( = 53, 9.4%), Japan ( = 29, 5.2%), and Canada ( = 25, 4.4%). Most of the included studies were case reports ( = 367, 63.4%), cross-sectional/prevalence studies ( = 130, 22.4%), and case series ( = 51, 8.8%). Only few longitudinal studies ( = 14, 2.4%), case-control studies ( = 12, 2.1%), and cohort studies (n = 5, 0.9%) were included in our review. Most studies focused on ( = 221, 39.3%), ( = 81, 14.4%), and ( = 52, 8.9%). For the 295 studies that used strain typing methods to compare bacteria from humans and pets, most used DNA banding pattern-based methods ( = 133, 45.1%) and DNA sequencing-based methods ( = 118, 40.0%).

Conclusion: Transmission of bacteria could occur in both directions: pets to humans (e.g., and ) and humans to pets (e.g., ). The majority of studies provided a low level of evidence of transmission (e.g., case reports), suggesting that more rigorous longitudinal, cohort, or case-control studies are needed to fully understand the risk of human-pet resistant bacterial transmission.